Chipping chisels



July22, 1958 F. F. MORGAN ET AL 2,843,92

CHIPPING CHISELS Filed July so, 1956 lnveiwroas mum-1m I Fneoamcx F-L. Ema B Jam aw mm, ,Wv

mm ATTORNEY nited Sttes Patent CHIPPING CHISELS Frederic Francis Llewellyn Morgan and Eric Basil James, Camborne, England, assignors to Holman Brothers Limited, Camborne, England, a British company Application July 30, 1956, Serial No. 601,067 Claims priority, application Great Britain August 10, 1955 8 Claims. (Cl. 30-1) This invention relates to chipping chisels and like tools, that is to say non-rotary tools which cause the generation of dust particles or chippings. It is now generally agreed that certain constituents of this dust are highly injurious to those working in the vicinity or others exposed to the dust for long periods. This applies particularly to the finer and lighter particles since whereas the heavier particles will settle comparatively rapidly the finer particles may remain airborne for long periods in suspension in the air being inhaled by those in the vicinity. Moreover the danger of such fine dust is aggravated by the fact that it is normally too fine to be visible in the ordinary way.

The invention is particularly applicable to pneumatically-operated chipping chisels, with which it has been found that very fine dust-like particles travel up the shaft of the chisel and then upwardly to the region of the operators face whence they are all too easily inhaled.

It is one object of the present invention to provide an improved means for extracting the dust-like particles before they can be inhaled.

According to the present invention a chipping chisel or like tool is provided with an attachable sleeve affording a coupling for connection with a source of suction, and defining, by itself or together with the chisel, one or more ducts leading from the suction coupling to the end of the sleeve nearer to the cutting edge of the chisel.

The, or each, duct may be formed between opposed, spaced surfaces of the chisel and sleeve respectively. For example the chisel shaft may have a flat, or either sleeve or shaft may be grooved. The or each duct may terminate in a suction mouth of elongated shape with its greater dimension extending peripherally along or round a part of the shaft of the chisel, and the mouth facing the cutting edge, where the dust is generated to be most effective in collecting dust travelling up the shaft, or to prevent the duct becoming closed by the operators grip, each wide duct may be divided into two by a stiffening piece. In some cases a single duct may be sufficient but of course there may be a number of ducts arranged peripherally all around the shaft.

The ducts may communicate with one another by virtue of a circumferential passage formed by a circumferential groove in the outer surface of the shaft or in the inner surface of the sleeve or in both.

The sleeve, which may be of resilient material, for example rubber, for ease in fitting and to enable a close fit to be obtained in spite of slight variations in tool sizes, may be manufactured separately to suit existing chisels so that an efficient dust extraction system can be obtained without the expense of specially manufactured tools, and the invention further comprises the sleeve for a combination as defined above.

The invention may be carried into practice in different ways but one specific embodiment will be described by way of example as applied to a pneumatically-operated chipping chisel, with reference to the accompanying drawing of which:

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Figure 1 shows a side view of the chisel shaft with the sleeve in longitudinal section, and

Figure 2 is an end view of the sleeve with the chisel removed, as seen frornthe end associated with the cutting edge-of the chisel.

The chipping chisel is generally of standard form, having a shaft 1 of octagonal cross-section, with a cutting edge 2 at one end and a shank 3 at the other end to which the blows from the pneumatic hammer can be applied.

Closely fitting around the shaft 1 of the chisel and extending from a point about 1 inch from its cutting edge 2 for perhaps 6 inches along the shaft is a hard rubber sleeve 4 which has at its end remote from the cutting edge 2 an internal circumferential locating ridge 5 which fits in a corresponding circumferential groove 6 machined in the external surface of the chisel shaft. Just on the cutting edge side of this locating ridge 5 the sleeve 4 is locally enlarged and affords an internal circumferential groove 7 which provides a circumferential duct surrounding the shaft of the chisel.

The inner surface of the sleeve 4 is octagonal-shaped to conform to the external shape of the chisel shaft 1, and is formed with two pairs of opposed grooves 11 to define with the co-operiating faces of the shaft 1, four elongated ducts two on either side of the shaft. These ducts at one end afford suction mouths opening into a funnel 11A surrounding the chisel cutting edge and at their other ends lead into the circumferential duct 7 around the shaft 1 which leads in turn into an oblique passage 12 in the locally-enlarged portion of the sleeve into which passage 12 a steel tube 13 is inserted. The projecting end of the steel tube 13 can be inserted into a flexible hose leading to an exhauster. In use, as dust is generated and travels up the chisel shaft it is drawn into the ducts 11 by the suction applied to them and removed to suitable disposal apparatus. Some dust which would not otherwise travel up the chisel may also be sucked up into the mouths of the ducts.

The sleeve 4 also acts as an effective shock-absorber to reduce vibration in the hands of the operator.

What we claim as our invention and desire to secure by Letters Patent is:

1. For use in combination with a chipping chisel, a tubular sleeve of resilient material having a longitudinal bore adapted to fit closely over the shaft of a chisel and provided adjacent one end with a coupling affording a suction port for connection to a source of suction, the internal surface of the bore of the sleeve being formed with a circumferential locating ridge at one end, and with a longitudinal groove leading at one end to the suction port and leading at the other end to a suction mouth at the other end of the sleeve.

2. A sleeve as claimed in claim 1 in which the internal surface of the bore of the sleeve is formed with a transverse groove into which the suction port leads, said internal surface also being formed with other longitudinal grooves in addition to said first-mentioned groove, all leading into the transverse groove and extending side by side over the majority of the length of the sleeve.

3. A sleeve as claimed in claim 2 in which the transverse groove extends circumferentially around the whole of the bore.

4. A sleeve as claimed in claim 1 in which the bore of the sleeve is of grooved regular polygonal section.

5. A sleeve as claimed in claim 1 made of hard rubber.

6. A sleeve as claimed in claim 1 which includes a flared open-ended resilient funnel secured to the end of the sleeve remote from the coupling.

7. A sleeve as claimed in claim 6 in which the axis of the coupling is oblique to the longitudinal axis of 3 4 the sleeve and in which the coupling is directed away, duct leading at one end to the suction port and leading at from the end of the sleeve carrying the funnel. the other end to a suction mouth at the other end of 8. For use in combination with a chipping chisel, a the sleeve.

tubular sleeve of resilient material having a longitudinal bore adapted to fit closely over the shaft of a chisel and 5 References Cited in the file of this patent provided adjacent one end with a coupling affording a suction port for connection to a source of suction, the UNITED STATES PATENTS internal surface of the bore of the sleeve being formed 2,280,007 Plateck Apr. 14, 1942 with a circumferential locating ridge at one end, and the 2,697,876 Blanchard Dec. 28, 1954 Wall of the sleeve being formed with a longitudinal air 10 2,748,472 Sheley et a1. June 5, 1956 

